(Circulation. 1999;99:2371-2377.)
© 1999 American Heart Association, Inc.
Clinical Investigation and Reports |
From Duke Clinical Research Institute, Durham, NC (K.W.M., R.A.H., C.B.G., C.G., M.J.A., D.L., J.M.M., L.G.B., C.M.M., R.M.C.); Harbin Clinic, Rome, Ga (M.A.S.); Thorax Center, Erasmus University, Rotterdam, The Netherlands (M.L.S., J.D.); and The Cleveland Clinic Foundation, Cleveland, Ohio (A.M.L., E.J.T.).
Correspondence to Kenneth W. Mahaffey, MD, PO Box 17969, Duke Clinical Research Institute, Duke University Medical Center, Durham, NC 27705. E-mail mahaf002{at}mc.duke.edu
| Abstract |
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Methods and ResultsWe studied the 10 948 patients with acute coronary syndromes without persistent ST-segment elevation who were randomly assigned to placebo or the platelet glycoprotein IIb/IIIa receptor inhibitor eptifibatide in the Platelet Glycoprotein IIb/IIIa in Unstable Angina: Receptor Suppression Using Integrilin Therapy (PURSUIT) trial to determine stroke rates, stroke types, clinical outcomes in patients with stroke, and independent baseline clinical predictors for nonhemorrhagic stroke. Stroke occurred in 79 (0.7%) patients, with 66 (0.6%) nonhemorrhagic, 6 intracranial hemorrhages, 3 cerebral infarctions with hemorrhagic conversion, and 4 of uncertain cause. There were no differences in stroke rates between patients who received placebo and those assigned high-dose eptifibatide (odds ratios and 95% confidence intervals 0.82 [0.59, 1.14] and 0.70 [0.49, 0.99], respectively). Of the 79 patients with stroke, 17 (22%) died within 30 days, and another 26 (32%) were disabled by hospital discharge or 30 days, whichever came first. Higher heart rate was the most important baseline clinical predictor of nonhemorrhagic stroke, followed by older age, prior anterior myocardial infarction, prior stroke or transient ischemic attack, and diabetes mellitus. These factors were used to develop a simple scoring nomogram that can predict the risk of nonhemorrhagic stroke.
ConclusionsStroke was an uncommon event in patients with acute coronary syndromes in the PURSUIT trial. These strokes are, however, associated with substantial morbidity and mortality rates. The majority of strokes were of nonhemorrhagic causes. Eptifibatide was not associated with an increase in intracranial hemorrhage, and no significant effect on nonhemorrhagic stroke was observed. We developed a useful nomogram for assigning baseline nonhemorrhagic stroke risk in this patient population.
Key Words: stroke coronary disease myocardial infarction glycoproteins receptors
| Introduction |
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The recently completed Platelet Glycoprotein IIb/IIIa in Unstable Angina: Receptor Suppression Using Integrilin Therapy (PURSUIT) trial is the largest trial to date of patients with acute coronary syndromes without persistent ST-segment elevation.16 We prospectively collected information about patients with suspected stroke to determine the incidence of stroke, stroke types, outcomes in patients with stroke, and the independent baseline clinical and demographic risk factors for nonhemorrhagic stroke in this patient population.
| Methods |
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Patients were randomly assigned in double-blind fashion to an intravenous bolus and infusion of placebo, 180 mm/kg bolus plus infusion of 1.3 µg/kg per minute of eptifibatide, or 180 µg/kg bolus plus infusion of 2.0 µg/kg per minute of eptifibatide. Per prespecified plan, after 3218 patients were randomized, an independent Data and Safety Monitoring Committee reviewed the safety data. The committee recommended dropping the lower dose because the high dose had an acceptable safety profile.
A study drug was to be infused until hospital discharge or up to 72 hours, whichever came first (or up to 96 hours in patients undergoing percutaneous intervention at 72 hours). All patients were to receive daily aspirin, and heparin was recommended but not required. Intravenous heparin was to be given as a 5000 U bolus and 1000 U/h infusion with adjustment to maintain activated partial thromboplastin time in the 50 to 70 seconds range. Lower doses were recommended for patients who weighed <70 kg. Other concomitant medications, diagnostic cardiac procedures, or percutaneous or surgical interventions were at the discretion of the treating physician.
Stroke Classification
Stroke was defined as an acute new neurological deficit
resulting in death or lasting for >24 hours. A Stroke Adjudication
Committee (see Appendix) was established to independently adjudicate
and categorize all suspected strokes. Patients with suspected strokes
were identified from the Case Report Form.
The evaluation of patients with stroke was prospectively planned. The protocol specified that all patients with a new neurological deficit undergo complete evaluation including brain imaging. Clinical notes, discharge summaries, neurological or neurosurgical consultation notes, autopsy reports, and results of computed tomographic or magnetic resonance imaging (MRI) studies were collected on all patients with suspected stroke. The committee reviewed all available medical records and determined by consensus if a stroke did or did not occur and if so, categorized the type of stroke. The Stroke Adjudication Committee members were blinded to treatment assignment.
Stroke Categories
Strokes were divided into 4 main categories: primary
hemorrhagic, nonhemorrhagic, hemorrhagic conversion of infarct, and
uncertain. Primary hemorrhagic was diagnosed if a focal collection of
intracranial blood was seen on brain imaging or at autopsy and was not
believed to represent hemorrhagic conversion. Nonhemorrhagic
stroke was categorized if there was a low-density lesion on computed
tomography, high-intensity lesion on MRI, or clinical evidence of a
stroke and no focal collection of intracranial hemorrhage on
brain imaging studies or at autopsy. Hemorrhagic conversion was
diagnosed if blood was present within an area of cerebral
infarction, but the event was not thought to represent a
primary hemorrhagic stroke. The uncertain classification was used if
there was clinical evidence of a stroke and no brain imaging or autopsy
data were available to determine the type of stroke.
Patient Functional Assessment
Functional status was determined for all patients with stroke at
hospital discharge or 30 days, whichever came first. Patients were
classified by site investigators as not disabled if they had no deficit
(no sequelae) or minor deficits (functional status unchanged) and as
disabled if they had moderate deficits (significant limitations of
activity) or severe deficits (unable to live independently or return to
work). The correlation of this classification of disability and direct
patient interviews in stroke survivors has been shown to be
excellent.9
Statistical Analysis
Continuous variables are shown as medians with 25th and 75th
percentiles. Discrete variables are shown as frequencies and
percentages. Stroke data for all 10 948 patients are included.
Analyses that include comparisons between treatment groups only
include the 9461 patients assigned placebo or high-dose eptifibatide
because the low-dose eptifibatide group was not contemporaneous with
the other 2 groups as the result of discontinuation of the low-dose arm
after the interim analysis by the Data Safety and Monitoring
Board (see Methods). Logistic regression modeling was used to determine
the univariable predictors of nonhemorrhagic stroke and the
multivariable baseline risk factors for nonhemorrhagic stroke.
Predictors were tested with the use of the Wald or likelihood
2 test. Results are presented as odds
ratios and 95% confidence intervals.
A scoring nomogram was created from the coefficients from the baseline multivariable regression modeling. Each independent predictor was assigned a score according to its predictive value. The sum of the scores indicates the probability of a nonhemorrhagic stroke, based on baseline predictors for individual patients.17
| Results |
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Table 3
shows the baseline clinical
characteristics for patients with and those without stroke and for
patients with nonhemorrhagic stroke. Patients with stroke were older
and more often female, had lower body weight and higher heart rate, and
more frequently had prior myocardial infarction, diabetes mellitus,
history of hypertension, hypercholesterolemia,
coronary artery bypass surgery, and history of stroke or
transient ischemic attack. Patients with stroke more commonly
experienced adverse in-hospital events including hypotension, atrial
fibrillation, congestive heart failure, cardiogenic shock, and
coronary artery bypass surgery (Table 4
).
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Table 5
shows the univariable
baseline factors associated with nonhemorrhagic stroke. Five
independent baseline clinical and demographic predictors of stroke
occurring by 30-day follow-up were identified (Table 6
). Higher heart rate was the most
important independent baseline clinical predictor; older age, previous
anterior myocardial infarction, prior stroke or transient
ischemic attack, and history of diabetes mellitus were the
other statistically significant predictors. Other possible but not
statistically significant predictors were prior
percutaneous intervention (P=0.09), history
of aspirin use (P=0.06), and history of
hypercholesterolemia (P=0.09). The
predicted probability in individual patients for nonhemorrhagic stroke
within 30-day follow-up can be calculated by using the nomogram in
Figure 2
.
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| Discussion |
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In patients with ST-segment elevation, acute myocardial infarction, the incidence of stroke in the era before the routine use of thrombolytic therapy was 1.7% to 3.2%.1 2 3 4 5 In the thrombolytic era, the incidence of stroke has decreased, but there is a higher proportion of intracranial hemorrhage (0.07% to 1.5%) and a lower rate of nonhemorrhagic stroke (0.1% to 1.3%).6 7 8 9 10 11 12 The rates observed for nonhemorrhagic stroke in the current study were similar to those for patients with acute myocardial infarction treated with thrombolysis and, as would be expected, the incidence of intracranial hemorrhage was lower. The observed rate of intracranial hemorrhage was 0.05% (6/10948) without evidence of an increase in the eptifibatide groups compared with placebo (4 patients vs 2 patients). These data support the safety of eptifibatide regarding intracranial hemorrhage.
The Global Use of Strategies to Open Occluded Arteries in acute coronary syndromes (GUSTO IIb) trial14 was the largest trial of patients with acute coronary syndromes prior to PURSUIT. In GUSTO IIb, 8011 patients with acute coronary syndromes without persistent ST-segment elevation were randomly assigned to intravenous heparin or the novel antithrombin, hirudin. All patients were to be treated with aspirin. The overall incidence of stroke was 0.8%. Nonhemorrhagic stroke occurred in 0.5% of patients and 0.09% of patients had a primary hemorrhagic stroke.14 No difference in stroke rates was observed by treatment assignment. These data are similar to the stroke rates in PURSUIT, in which patients were to be treated with heparin and aspirin and randomly assigned to the glycoprotein IIb/IIIa receptor inhibitor eptifibatide or to placebo. The patients in PURSUIT were more often female (35% vs 33%), younger (64 vs 66 years), heavier (78 vs 76 kg), and had lower enrollment systolic blood pressure (130 vs 139 mm Hg), lower heart rate (72 vs 74 bpm) and were more likely to have a history of diabetes (23% vs 19%), hypertension (55% vs 48), or previous coronary intervention (13% vs 12%) compared with the GUSTO IIb population. However, the impact of these factors on stroke rates in the 2 trials is unknown.
No previous studies have determined the risk factors for stroke in the unstable angina population to use for comparison with our results. In the GUSTO I trial of >41 000 patients treated with thrombolysis for acute myocardial infarction, the baseline independent risk factors for nonhemorrhagic stroke were similar to those identified for the PURSUIT population.13 In GUSTO I, as in PURSUIT, older age, higher heart rate, history of stroke or transient ischemic attack, and diabetes mellitus were independent baseline predictors of stroke.18 Prior anterior myocardial infarction was not a risk factor in the GUSTO I stroke prediction model, but prior angina was an independent predictor. A history of hypertension was also an independent predictor in the GUSTO I population, but it was not in the PURSUIT nonhemorrhagic stroke model, although it did achieve borderline statistical significance in univariable analysis. The reason higher heart rate is an independent predictor for nonhemorrhagic stroke is not clear from these data, but heart rate may correlate with larger infarctions that predispose patients to a higher likelihood of atrial arrhythmia and left ventricular thrombi.
The clinical outcomes of stroke patients with unstable angina/nonQ-wave myocardial infarction have not been previously reported. In PURSUIT, stroke was associated with substantial morbidity and mortality rates. In GUSTO I, the percentage of nonhemorrhagic stroke patients who died or were disabled was comparable with that in the PURSUIT population (57% vs 54%).9
The incidence of nonhemorrhagic stroke in patients assigned high-dose eptifibatide compared with placebo was similar (0.6% vs 0.7%, respectively; P=0.53). Treatment assignment was not a statistically significant predictor of nonhemorrhagic stroke in the univariable or multivariable analyses. The overall number of strokes was small; therefore definitive conclusions cannot be made about the potential risks or benefits of glycoprotein IIb/IIIa receptor blockade on the incidence of nonhemorrhagic stroke from these data. A lower incidence of nonhemorrhagic stroke in the eptifibatide group would have been consistent with the known benefits of antiplatelet therapy in decreasing the incidence of stroke in patients with acute myocardial infarction or prior stroke as well as in other high-risk patient groups including unstable angina.19 Ongoing studies of prolonged oral glycoprotein IIb/IIIa receptor antagonists in patients with acute coronary syndromes and cerebrovascular disease will provide more definitive data about treatment benefits with such agents in these patient populations.
Study Limitations
Our study has several limitations. The baseline predictors of
stroke may not account for all the risk for stroke in this patient
population. Fifty percent of nonhemorrhagic strokes occurred >6.5 days
after enrollment, and we were not able to account for in-hospital
procedures or events that may be associated with stroke, primarily
because of the relatively small sample size and limited regression
modeling that could be performed. There was no systematic assessment of
the cardiac rhythm at the time of study enrollment; therefore atrial
fibrillation was not included in the prediction model. However, only
159 (1.5%) patients had atrial fibrillation reported on the Case
Report Form before or within 4 hours of study enrollment, and only 2 of
these patients had nonhemorrhagic stroke.
The mechanism of the strokes, particularly the nonhemorrhagic strokes, was not assessed. However, systematic review of all suspected strokes by the Stroke Adjudication Committee, which included analysis of computed axial tomographic data, MRI data, or autopsy results in 80% of patients, allowed determination of stroke types in a majority of cases, and the number of "unknowns" was small.
The logistic regression model and associated scoring nomogram were developed with the use of only 64 nonhemorrhagic strokes and therefore require validation in a larger patient population. However, the similarity to the prediction model from the GUSTO-I trial is supportive. Finally, these results are only applicable to patients with acute coronary syndromes without persistent ST-segment elevation treated with heparin and aspirin and should not be generalized to all patients with acute coronary syndromes.
Conclusions
Stroke was an uncommon event in patients with acute
coronary syndromes without persistent ST-segment elevation
treated with antiplatelet and antithrombin therapy in the PURSUIT
trial. The majority of strokes were of nonhemorrhagic causes. Despite
the low incidence of stroke, its prevalence is substantial because more
than 1 million patients present each year with nonST-segment
elevation acute coronary syndromes to hospitals in the United
States, with similar numbers in Western Europe. Therefore >7000
patients with acute coronary syndromes in the United States
alone have a stroke, and these strokes are associated with significant
morbidity and mortality rates. The use of eptifibatide, a
glycoprotein IIb/IIIa receptor antagonist, was
not associated with an increased incidence of intracranial
hemorrhage, and we observed no significant effect on the
occurrence of nonhemorrhagic stroke. Higher heart rate, older age,
prior stroke or transient ischemic attack, prior anterior
myocardial infarction, and diabetes mellitus were independent baseline
predictors of nonhemorrhagic stroke. Physicians can use these factors
to determine the probability of nonhemorrhagic stroke with a simple
scoring nomogram (Figure 2
). The impact of stroke risk
assessment on patient management requires further study.
| Acknowledgments |
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| Appendix 1 |
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Received September 14, 1998; revision received February 3, 1999; accepted February 16, 1999.
| References |
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